The Leader Principle was a key pillar of fascism, vesting both absolute power and responsibility in one's leader. After seeing the principle in action on Nazi Ekos, James T. Kirk identified it as the main problem with the Nazi ideology, bigger even then the evil of individual leaders. Leonard McCoy explained it to Spock as meaning that despite their good intentions, their power usually lead them to attempt to "play God". (TOS: "Patterns of Force" )